Compressor components having an airfoil, such as a compressor blade, are held within a rotating disk or shaft and are designed to rotate at a high rate of speed in order to compress a fluid passing through, such as air. A compressor typically comprises a plurality of stages, or rotating disks of blades, of diminishing diameter that raise the pressure and temperature, of the working fluid at each stage to a pre-determined level at the compressor exit.
Axial compressors having multiple stages are commonly used in gas turbine engines for increasing the pressure and temperature of air to a pre-determined level at which point fuel can be mixed with the air and the mixture ignited. The hot combustion gases then pass through a turbine to provide either a propulsive output or mechanical output.
Compressor components, such as blades and vanes, are located near an inlet of the engine, and as such, are exposed to impact by foreign objects, dirt, and other debris, that can lead to erosion of the airfoil, especially along its leading edge, and reduced overall efficiency and higher fuel consumption rates. Often times, for increased power output and engine cleaning, operators of gas turbine engines waterwash the compressor, which as one skilled in the art understands is spraying a stream of demineralized water into the compressor inlet at regular cleaning intervals, such as one a day. Alternatively, operators have also installed inlet fogging of the compressor, which inject small droplets of fog into the inlet through special injection nozzle and high pressure pumps. These enhancements, while increasing the power output, can also increase erosion to the airfoil. Significant erosion of the airfoil leading edge can result in the leading edge being a life-limiting factor for the blade. Furthermore, as a blade rotates, it will have a series of vibratory modes that can cause high stress regions depending on the blade geometry. Where high stress regions coincide with other life-limiting factors, such as leading edge erosion, fatigue and failure of the blade are known to occur. When a compressor blade fails, at least the airfoil portion travels downstream through the compressor, damaging subsequent stages of compressor blades and vanes, causing damage significant enough to force an engine shutdown and major repair.